Our cell phones and tablets have transformed the way we hold our bodies—and not for the better. Looking down at your device is like having a 60-pound weight on your neck, according to a spine surgeon.

That's like having an eight-year old sitting on your head while you're standing trying to read your text messages, The Atlantic points out.

Dr. Kenneth K. Hansraj, chief of spine surgery at New York Spine Surgery & Rehabilitation Medicine, developed the computer model above. As you might expect, moving your head forward and having that amount of force on your neck and spine isn't good for your health—and the average person spends two to four hours a day in this position. Dr. Hansraj's paper, published in the Surgical Technology International journal, notes that good posture is having your ears aligned with the shoulders and your shoulder blades back. This lowers body stress and decreases cortisol. Poor posture, on the other hand, stresses the spine and can lead to early wear, tear, generation, and maybe surgery.